(a) Field of the Invention
This invention relates to novel furo[3,4-b]quinoline derivatives, to processes for their preparation, to intermediates used for the process, to methods for using said derivatives and to pharmaceutically acceptable compositions of said derivatives.
The furo[3,4-b]quinoline derivatives possess valuable pharmacologic properties. For example, these derivatives are useful for treating hypertension and microbial infections in a mammal at dosages which do not elicit undesirable side effects. The combination of these pharmacologic properties together with a low order of toxicity render the furo[3,4-b]quinoline derivatives of the invention therapeutically useful.
(b) Description of the Prior Art
Only a rather limited number of reports dealing with furo[3,4-b]quinoline derivatives have been published. For example, some furo[3,4-b]quinolines that can be considered are: acridinic anhydride, see Hozer and V. Niementowski, J. Prakt Chem., 116, 45 and 50 (1927) and "Beilstein's Handbuch der Organischen Chemie, Vierte Auglage", 11, 27, p. 311; substituted and unsubstituted furo[3,4-b]quinolin-1(3H)-ones, see E. A. Fehnel, et al., J. Org. Chem., 23, 1996 (1958), A. Godard et al., Bull. Soc. Chem. Fr., 906 (1971), G. Quequiner and A. Godard, C.R. Acad. Sci. Series C, 269, 1646 (1969) and L. Neilands and G. Vanags, Khim. Geterotskikl. Soedin. Akad. Naulk. Latv. SSR, 1965 (6), p. 884-8 (CA 64 12638 h): furo[3,4-b]quinolin-3(1H)-one, see G. Quequiner and A. Godard, cited above; 1-methyl-2-carboxy-3-hydroxymethyl-4(1H)-quinolone lactone, see J. R. Prince, Amst. J. Sci. Research 2A, 249 (1949); and 1,1,3,3-tetraalkyl-1,3-dihydrofuro[3,4-b]quinolines, see I. K. Korobitsyna et al., Zhur. Obshchei Khim., 31, 836 (1961). The compounds of the prior art are readily distinguished from the compounds of the present invention by existing at different oxidation states as well as having different substituents on the furo[3,4-b]quinoline nucleus.